> > +static int tpk_write_room(struct tty_struct *tty)
> > +{
> > + int ret = tpk_space;
> > +
> > + /* allow char by char under max pressure */
> > + if (tpk_space == 0)
> > + tpk_space = 1;
>
> That won't do what you think, the ldisc will keep seeing progress and
> generate millions of 1 byte I/Os in a loop !
>
Somewhat changed to slowly increase delay in write, if ratelimiting
doesn't end.
> Otherwise looks excellent.
>
Thanks to you.
>
> > + switch (cmd) {
> > + /* Stop TIOCCONS */
> > + case TIOCCONS:
> > + return -EOPNOTSUPP;
>
> And I'll fix this bit up to work properly in the core code.
>
>
> With my devices.txt owner hat on I'll allocate the minor as you suggest
> (and double check this causes no problems), with my tty hat on can you
> send it to GregKH for merging into the tree.
I am not sure if i understand. Should i exclude devices.txt from patch
before sending it to GregKH?
Samo
---
Signed-off-by: Samo Pogacnik <samo_pogacnik@xxxxxxx>
diff --git a_linux/Documentation/devices.txt b_linux/Documentation/devices.txt
index 53d64d3..71aef33 100644
--- a_linux/Documentation/devices.txt
+++ b_linux/Documentation/devices.txt
@@ -239,6 +239,7 @@ Your cooperation is appreciated.
0 = /dev/tty Current TTY device
1 = /dev/console System console
2 = /dev/ptmx PTY master multiplex
+ 3 = /dev/ttyprintk User messages via printk TTY device
64 = /dev/cua0 Callout device for ttyS0
...
255 = /dev/cua191 Callout device for ttyS191
diff --git a_linux/drivers/char/Kconfig b_linux/drivers/char/Kconfig
index 3141dd3..5c38a06 100644
--- a_linux/drivers/char/Kconfig
+++ b_linux/drivers/char/Kconfig
@@ -485,6 +485,20 @@ config LEGACY_PTY_COUNT
When not in use, each legacy PTY occupies 12 bytes on 32-bit
architectures and 24 bytes on 64-bit architectures.
+config TTY_PRINTK
+ bool "TTY driver to output user messages via printk"
+ default n
+ ---help---
+ If you say Y here, the support for writing user messages (i.e.
+ console messages) via printk is available.
+
+ The feature is useful to inline user messages with kernel
+ messages.
+ In order to use this feature, you should output user messages
+ to /dev/ttyprintk or redirect console to this TTY.
+
+ If unsure, say N.
+
config BRIQ_PANEL
tristate 'Total Impact briQ front panel driver'
depends on PPC_CHRP
diff --git a_linux/drivers/char/Makefile b_linux/drivers/char/Makefile
index f957edf..ed60f45 100644
--- a_linux/drivers/char/Makefile
+++ b_linux/drivers/char/Makefile
@@ -11,6 +11,7 @@ obj-y += mem.o random.o tty_io.o n_tty.o tty_ioctl.o tty_ldisc.o tty_buffer.o t
obj-$(CONFIG_LEGACY_PTYS) += pty.o
obj-$(CONFIG_UNIX98_PTYS) += pty.o
+obj-$(CONFIG_TTY_PRINTK) += ttyprintk.o
obj-y += misc.o
obj-$(CONFIG_VT) += vt_ioctl.o vc_screen.o selection.o keyboard.o
obj-$(CONFIG_BFIN_JTAG_COMM) += bfin_jtag_comm.o
diff --git a_linux/drivers/char/ttyprintk.c b_linux/drivers/char/ttyprintk.c
new file mode 100644
index 0000000..2fefa93
--- /dev/null
+++ b_linux/drivers/char/ttyprintk.c
@@ -0,0 +1,297 @@
+/*
+ * linux/drivers/char/ttyprintk.c
+ *
+ * Copyright (C) 2010 Samo Pogacnik
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the smems of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ */
+
+/*
+ * This pseudo device allows user to make printk messages. It is possible
+ * to store "console" messages inline with kernel messages for better analyses
+ * of the boot process, for example.
+ */
+
+#include <linux/sched.h>
+#include <linux/delay.h>
+#include <linux/ratelimit.h>
+#include <linux/device.h>
+#include <linux/serial.h>
+#include <linux/tty.h>
+
+struct ttyprintk_port {
+ struct tty_port port;
+ struct mutex port_write_mutex;
+};
+
+static struct ttyprintk_port tpk_port;
+
+#define TTY_PRINTK_STR_SIZE 508
+static int tpk_space = TTY_PRINTK_STR_SIZE;
+static const char *tpk_tag = "[U] "; /* U for User */
+
+/*
+ * Ratelimiting support to handle to much output to this device,
+ * because of explicit writes or because of unintentional loop
+ * setup (caught printks again sent to this device).
+ */
+static struct ratelimit_state ttyprintk_rs = {
+ .interval = DEFAULT_RATELIMIT_INTERVAL,
+ .burst = DEFAULT_RATELIMIT_BURST,
+};
+
+static int tpk_ratelimiting;
+
+#define ttyprintk_printk(fmt, ...) \
+{ \
+ printk(KERN_INFO fmt, ##__VA_ARGS__); \
+}
+
+/*
+ * Our private ratelimit function, to suppress its printk warnings about
+ * missed callbacks, which are irrelevant in a flow control mechanism.
+ */
+static void ttyprintk_ratelimit(struct ratelimit_state *rs, int count)
+{
+ /* clear ratelimit missed callbacks counter */
+ rs->missed = 0;
+ if (__ratelimit(rs)) {
+ tpk_ratelimiting = 0;
+ tpk_space = TTY_PRINTK_STR_SIZE;
+ rs->burst = DEFAULT_RATELIMIT_BURST;
+ } else {
+ tpk_ratelimiting = 1;
+ if (TTY_PRINTK_STR_SIZE > count)
+ tpk_space = TTY_PRINTK_STR_SIZE - count;
+ else
+ tpk_space = 0;
+ }
+}
+
+/*
+ * Our simple preformatting supports transparent output of (time-stamped)
+ * printk messages (also suitable for logging service):
+ * - any cr is replaced by nl
+ * - adds a ttyprintk source tag in front of each line
+ * - too long message is fragmeted, with '\'nl between fragments
+ */
+static int tpk_printk(const unsigned char *buf, int count)
+{
+ static char tmp[TTY_PRINTK_STR_SIZE + 4];
+ static int curr;
+ int i = curr;
+
+ if (buf == NULL) {
+ /* flush tmp[] */
+ if (curr > 0) {
+ /* non nl or cr terminated message - add nl */
+ tmp[curr + 0] = '\n';
+ tmp[curr + 1] = '\0';
+ ttyprintk_printk("%s%s", tpk_tag, tmp);
+ curr = 0;
+ }
+ return i;
+ }
+
+ for (i = 0; i < count; i++) {
+ tmp[curr] = buf[i];
+ if (curr < TTY_PRINTK_STR_SIZE) {
+ switch (buf[i]) {
+ case '\r':
+ /* replace cr with nl */
+ tmp[curr + 0] = '\n';
+ tmp[curr + 1] = '\0';
+ ttyprintk_printk("%s%s", tpk_tag, tmp);
+ curr = 0;
+ if (buf[i + 1] == '\n')
+ i++;
+ break;
+ case '\n':
+ tmp[curr + 1] = '\0';
+ ttyprintk_printk("%s%s", tpk_tag, tmp);
+ curr = 0;
+ break;
+ default:
+ curr++;
+ }
+ } else {
+ /* end of tmp buffer reached: cut the message in two */
+ tmp[curr + 1] = '\\';
+ tmp[curr + 2] = '\n';
+ tmp[curr + 3] = '\0';
+ ttyprintk_printk("%s%s", tpk_tag, tmp);
+ curr = 0;
+ }
+ }
+ if ((tpk_ratelimiting == 0) && (curr > 0)) {
+ /* non nl or cr terminated message - add nl */
+ tmp[curr + 0] = '\n';
+ tmp[curr + 1] = '\0';
+ ttyprintk_printk("%s%s", tpk_tag, tmp);
+ curr = 0;
+ }
+
+ return count;
+}
+
+/*
+ * TTY operations open function.
+ */
+static int tpk_open(struct tty_struct *tty, struct file *filp)
+{
+ tty->driver_data = &tpk_port;
+
+ return tty_port_open(&tpk_port.port, tty, filp);
+}
+
+/*
+ * TTY operations close function.
+ */
+static void tpk_close(struct tty_struct *tty, struct file *filp)
+{
+ struct ttyprintk_port *tpkp = tty->driver_data;
+
+ mutex_lock(&tpkp->port_write_mutex);
+ /* flush tpk_printk buffer */
+ tpk_printk(NULL, 0);
+ tpk_space = TTY_PRINTK_STR_SIZE;
+ tpk_ratelimiting = 0;
+ mutex_unlock(&tpkp->port_write_mutex);
+
+ tty_port_close(&tpkp->port, tty, filp);
+}
+
+/*
+ * TTY operations write function.
+ */
+static int tpk_write(struct tty_struct *tty,
+ const unsigned char *buf, int count)
+{
+ static unsigned int tpk_write_delay;
+ struct ttyprintk_port *tpkp = tty->driver_data;
+ int ret;
+
+
+ /* exclusive use of tpk_printk within this tty */
+ mutex_lock(&tpkp->port_write_mutex);
+ ttyprintk_ratelimit(&ttyprintk_rs, count);
+ if (tpk_ratelimiting == 0) {
+ tpk_write_delay = 0;
+ } else {
+ /* increase delay under pressure upto 10 secs */
+ if (tpk_write_delay < 1000000)
+ tpk_write_delay++;
+ msleep_interruptible(tpk_write_delay / 100);
+
+ /* eliminate delay in ratelimiting */
+ ttyprintk_rs.burst = 1;
+ ttyprintk_rs.begin = 0;
+ __ratelimit(&ttyprintk_rs);
+ }
+
+ ret = tpk_printk(buf, count);
+ mutex_unlock(&tpkp->port_write_mutex);
+
+ return ret;
+}
+
+/*
+ * TTY operations write_room function.
+ */
+static int tpk_write_room(struct tty_struct *tty)
+{
+ int ret = tpk_space;
+
+ /* just in case we reach zero space, let one char available */
+ if (tpk_space == 0)
+ tpk_space = 1;
+
+ return ret;
+}
+
+/*
+ * TTY operations ioctl function.
+ */
+static int tpk_ioctl(struct tty_struct *tty, struct file *file,
+ unsigned int cmd, unsigned long arg)
+{
+ struct ttyprintk_port *port;
+
+ port = tty->driver_data;
+
+ if (!port)
+ return -EINVAL;
+
+ switch (cmd) {
+ /* Stop TIOCCONS */
+ case TIOCCONS:
+ return -EOPNOTSUPP;
+ default:
+ return -ENOIOCTLCMD;
+ }
+ return 0;
+}
+
+static const struct tty_operations ttyprintk_ops = {
+ .open = tpk_open,
+ .close = tpk_close,
+ .write = tpk_write,
+ .write_room = tpk_write_room,
+ .ioctl = tpk_ioctl,
+};
+
+struct tty_port_operations null_ops = { };
+
+static struct tty_driver *ttyprintk_driver;
+
+static int __init ttyprintk_init(void)
+{
+ int ret = -ENOMEM;
+ void *rp;
+
+ ttyprintk_driver = alloc_tty_driver(1);
+ if (!ttyprintk_driver)
+ return ret;
+
+ ttyprintk_driver->owner = THIS_MODULE;
+ ttyprintk_driver->driver_name = "ttyprintk";
+ ttyprintk_driver->name = "ttyprintk";
+ ttyprintk_driver->major = TTYAUX_MAJOR;
+ ttyprintk_driver->minor_start = 3;
+ ttyprintk_driver->num = 1;
+ ttyprintk_driver->type = TTY_DRIVER_TYPE_CONSOLE;
+ ttyprintk_driver->init_termios = tty_std_termios;
+ ttyprintk_driver->init_termios.c_oflag = OPOST | OCRNL | ONOCR | ONLRET;
+ ttyprintk_driver->flags = TTY_DRIVER_RESET_TERMIOS |
+ TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
+ tty_set_operations(ttyprintk_driver, &ttyprintk_ops);
+
+ ret = tty_register_driver(ttyprintk_driver);
+ if (ret < 0) {
+ printk(KERN_ERR "Couldn't register ttyprintk driver\n");
+ goto error;
+ }
+
+ /* create our unnumbered device */
+ rp = device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 3), NULL,
+ ttyprintk_driver->name);
+ if (IS_ERR(rp)) {
+ printk(KERN_ERR "Couldn't create ttyprintk device\n");
+ ret = PTR_ERR(rp);
+ goto error;
+ }
+
+ tty_port_init(&tpk_port.port);
+ tpk_port.port.ops = &null_ops;
+ mutex_init(&tpk_port.port_write_mutex);
+
+ return 0;
+
+error:
+ put_tty_driver(ttyprintk_driver);
+ ttyprintk_driver = NULL;
+ return ret;
+}
+module_init(ttyprintk_init);
--
To unsubscribe from this list: send the line "unsubscribe linux-embedded" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
